﻿<p><em>IfcAsymmetricIShapeProfileDef</em>
defines a section profile that provides the defining parameters of a
singly symmetric I-shaped section. Its parameters and orientation relative to the
position coordinate system are according to the following illustration.
The centre of the position coordinate system is in the profile's centre
of the bounding box.</p>

<p>The overall width of the profile is implicitly given by the maximum of
the bottom flange width and the top flange width.</p>

<p><em>IfcAsymmetricIShapeProfileDef</em> can also be used to model rail profiles
if the application scenario does not require a full explicit shape model of the
rail profile. Alternatively, <em>IfcArbitraryClosedProfileDef</em> can be
used to provide the exact shape of rail profiles. Either way, a reference
to an external document or library should be provided to further define the
profile as described at <em>IfcProfileDef</em>.</p>

<blockquote class="history">
HISTORY&nbsp; New entity in IFC2x2.
</blockquote>

<blockquote class="change-ifc2x3">
IFC2x3 CHANGE&nbsp; All profile origins are now in the center of the bounding box. The attribute <em>CentreOfGravityInY</em> has been made OPTIONAL.
</blockquote>

<blockquote class="change-ifc2x4">
IFC4 CHANGE&nbsp; 
Supertype changed from <em>IfcIShapeProfileDef</em> to <em>IfcParameterizedProfileDef</em>. Attributes which were inherited from <em>IfcIShapeProfileDef</em> are now defined directly at <em>IfcAsymmetricIShapeProfileDef</em> and have been partially renamed but were not reordered.<br>
Bottom flange may be narrower than top flange.<br>
Type of <em>TopFlangeFilletRadius</em> relaxed to allow for zero radius.<br>
Trailing attribute <em>CentreOfGravityInY</em> deleted, use respective property in <em>IfcExtendedProfileProperties</em> instead.<br>
Attributes <em>BottomFlangeEdgeRadius</em>, <em>BottomFlangeSlope</em>, <em>TopFlangeEdgeRadius</em>, <em>TopFlangeSlope</em> added.
</blockquote>

<p>Figure 2 illustrates parameters of the asymmetric I-shaped section definition. The parameterized profile defines its own position coordinate system. The underlying coordinate system is defined by the swept area solid that uses the profile definition. It is the xy plane of:</p>
      <ul>
        <li><em>IfcSweptAreaSolid.Position</em></li>
      </ul>
<p>By using offsets of the position location, the parameterized profile can be positioned centric (using x,y offsets = 0.), or at any position
relative to the profile. The parameterized profile is defined by a set of parameter attributes.  In the illustrated example, the 'CentreOfGravityInY' property in <em>IfcExtendedProfileProperties</em>, if provided, is negative.</p>

<table>
<tr><td><img style="border: 0px solid ; width: 400px; height: 300px;" alt="asymmetric I shape profile" src="../../../figures/ifcasymmetricishapeprofiledef.gif"></td></tr>
<tr><td><p class="figure">Figure 2 &mdash; Assymetric I-shape profile</p></td></tr>
</table>